No. 497] THE BUREAU OF FISHERIES 337 



workers; but all such attempts gave negative results, 

 only one form of curve being obtained. The contraction 

 is very rapid, and the height of the curve varies, within 

 certain limits, as the strength of the stimulus. The re- 

 laxation is rapid at first, but later takes place more 

 slowly. Summation is more or less regular. With con- 

 stant current there were generally obtained the usual 

 stimulations at the make and break of the circuit. The 

 form of the curves varied greatly, however, according to 

 the direction in which the current traversed the muscle. 

 The weak constant current caused a marked relaxation of 

 the muscle, only when passing through it in an ascending 

 direction. Fatigue in Limulus seems more or less 

 regular. As it progresses, there is a noticeably greater 

 interval between the contraction and the relaxation. The 

 latter also becomes much slower. After this stage, the 

 height of contraction gradually diminishes until no re- 

 sponse at all is obtained. 



George Gr. Scott, A.M., instructor in biologv, College of 

 the City of New York.-(l)T7*e Effect of Poisons, at Dif- 

 ferent Temperatures, on Fundulus heteroclitus. Sixteen 

 experiments are recorded. In each case two lots of fish 

 were used, one lot being kept at the temperature of the 

 laboratory, i. e., about 70° F., while the other lot was kept 

 at a lower temperature, i. e., about 50° F. Different 

 dilute solutions of a variety of organic and inorganic 

 poisons were used. In eleven of these experiments it was 

 distinctly shown that the effect of the poison was greater 

 at the higher temperature ; in four, the result showed no 

 difference; while in one, the result was opposite to the 

 first named effect. (2) The Effect of Change in Density 

 of the Water on the Blood of Fundulus heteroclitus. It 

 has been recently shown by Sumner that there may occur 

 a passage of fluids into or out of the bodies of teleost 

 fishes when the density of the medium to which they are 

 accustomed has been sufficiently changed. This has been 

 proved by demonstrating the occurrence of changes of 



